For some post-feminists, it's all about choice and empowerment: the opportunity to overthrow repression of all kinds. Others argue that lads' mags have brainwashed us into believing that what suits Nuts coincides precisely – ta-dah! – with our "innermost desires".

It was reported this week that Miley Cyrus is struggling with the transition from "wholesome" child star to "raunchy" adult artist. Interesting – first that these appear to be her only options; and second because, for many children, the line between childish naivety and adult raunch begins considerably sooner.

Recently, Primark was forced to withdraw its padded bikini-bra for seven-year-olds. A quick trawl of the high street reveals dominatrix-inspired high-heeled shoes to fit an eight-year-old; padded bras for pre-teens; T-shirts with "Future Wag" and "England Babe" emblazoned across the chest.

We may instinctively recoil from products like these; but we may also think twice about criticising them too loudly. Raunch culture has been extraordinarily successful at rebranding all criticism as prudishness – allowing it to march to the heart of mainstream culture, almost unchallenged.

What's wrong, after all, with little girls dressing up? Or with sexiness (the subtextual conclusion is, of course, " … you sour old prude".)

But you don't have to be a prude (or, as it happens, a feminist – the two terms are still used interchangeably) to believe that little girls should not be told that their value exists in appealing the opposite sex; nor that it's sad for girls – and boys – to grow up confusing a porn-inspired pastiche of female sexuality with the real thing.

Not only sad, but corrosive to their mental health. A 2007 study by the American Psychological Association found that girls' "cognitive functioning, physical and mental health, and healthy sexual development" was being damaged by their media portrayal as sex objects. A Girl Guides study similarly found that premature sexualisation was a "key influence" in rising anxiety felt by girls.

So, who can turn back the creeping tide? Parents – absolutely. While a minority love to dress their kids like teetering mini-Jordans, most of us are just too damn tired to argue. But if we don't want padded bras for nine-year-olds to become the norm, we mustn't buy them. It's time to learn to hold the line, even against a nine-year-old.

Retailers, too, must step up to the plate. Some will argue that it is not their job to make judgments on parents' behalf. But as a general rule, we don't allow the market a free rein if its imperatives conflict with the well-being of children. We self-regulate – and if that doesn't work, we legislate.

So it's extremely heartening to see that many retailers have agreed to shoulder some of the burden, alongside parents, by ensuring that the products they sell don't sexualise children. With luck, we can buy children a little more time to actually be children – before we send them out to negotiate raunch culture for themselves.